How to Use a Tung Oil Finish

A pure or polymerized tung oil finish is easy to use and will produce beautiful results on any type of wood. Usually applied to unfinished wood, but can be used over oil base stain.

Existing finishes must be removed, as this is a penetrating oil. It needs to penetrate deeply into the wood fibers and pores.

Preparation

New wood needs to sanded smooth prior to application. This finish will not build a film like varnish, so most of the sanding should be done before any tung oil finish is applied. If the wood is ruff start with medium grit sand paper and then finish with a fine grit, always sand in the direction of the grain.

After sanding, all repairs can be done. Any holes or cracks can be filled with a wood filler. If a wood stain is to be used choose a stainable filler.

For wood without any stain choose a colored wood filler that approximately matches the woods color. Do a final sanding if necessary and remove all dust with tack rags.

Staining

Any oil base wood stain can be applied. A tung oil finish has an amber color that will change or enhance the stain color. Choose traditional colors that will be subtle and still enhance the wood grain.

When in doubt apply the stain and finish to a scrap piece of similar wood before staining.

Applying Tung Oil

A tung oil finish can be applied pure or thinned up to 50% with mineral spirits or turpentine. Thinning the first coat will increase penetration, decrease the drying time and produce better results.

A typical application is by hand rubbing. Dip a soft cloth or rag into the finish and rub onto the wood. Keep applying until the wood is saturated. Use a natural bristle brush for hard to reach areas. Allow each coat to remain on the surface for 20-30 minutes. Wipe all areas to remove any excess. Check for drips or runs after another few minutes.

Drying is a slow process and will occur between 24-48 hours. This depends on the porosity of the wood and whether you thinned the finish. It will take 3-4 coats to achieve a waterproof surface. You can lightly sand or buff with extra fine steel wool between coats.

For exterior use, brushing will be the best method for application. The first application should be thinned to increase penetration. Pick up all drips and runs after 30 minutes. Apply 4-6 coats on new, very porous woods like cedar.

Maintenance

Maintenance is very easy. Light scratches can be gone with a light sanding and the addition of another coat of tung oil finish. Interior wood surfaces might need another coat every 2-4 years and exterior wood 1-2 years depending on exposure to sun light and wood species.